5.The flexible diaphragm of the lid-locking device is visible when viewing the underside of the kettle lid. Make certain diaphragm material is not torn or punctured. If it is, contact your local Hobart service office for immediate replacement.
6.Dip O-Ring in cooking oil for lubrication, and insert it into groove. IMPORTANT: First, press O-Ring into place at the 12-, 6-, 3- and 9-o'clock positions (Fig. 20). Using finger pressure only, stretch and work O-Ring into groove until it is seated all the way around. Apply pressure straight down. Do not twist or roll ring into groove; this may fracture the skin of the ring.
12 O’CLOCK
6 O’CLOCK
PL-50399 
Fig. 20
7. To reinstall the kettle tilt lid, reverse the procedure described in step 1.
Pressure-Relief Valve
Once a week, operate the pressure-relief valve release ring (see Fig. 10) by lifting it up and then back down.
Monthly Cleaning
Exhaust Tank
Remove the exhaust tank at the rear of the fryer and flush it out with hot water. To remove the exhaust tank:
1.Remove 4 screws holding exhaust vent in place (Fig. 21) and lift exhaust vent up.
2.If exhaust pipe (Fig. 21) hinders removal of the exhaust tank, unscrew pipe and remove it.
3.Disconnect drain pipe (Fig. 21) that runs from pressure-regulator housing to exhaust tank at the union.
4.Remove bolt from exhaust tank drain line clamp (Fig. 22).